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Table of Contents ( MARK ONE ) X UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31 , 2020 FORM 10 - K or TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 000-11676 BEL FUSE INC . 206 Van Vorst Street Jersey City , NJ 07302 ( 201 ) 432-0463 ( Address of principal executive offices and zip code ) ( Registrant's telephone number , including area code ) New Jersey ( State of incorporation ) Title of Each Class Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol BELFA 22-1463699 ( I.R.S. Employer Identification No. ) BELFB Class A Common Stock ( $ 0.10 par value ) Class B Common Stock ( $ 0.10 par value ) Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by checkmark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Indicate by checkmark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Name of Each Exchange on which Registered NASDAQ Global Select Market NASDAQ Global Select Market Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes Yes Yes > Yes No | No | No No